Year 8 Science (ALL) Flashcards
Name the two poles of a magnet.
North (-seeking) and south (-seeking) poles.
What is a magnetic field?
A region in which there is a force on a magnet or magnetic material.
In which direction do field lines always point?
From the north pole to the south pole.
Name two magnetic poles that will attract each other.
North and a south.
Name two magnetic poles that will repel each other.
North and a north, or south and a south.
State two ways you can find out the shape of a magnetic field.
Iron filings, plotting compasses
State the type of material you can use for the core of an electromagnet.
Soft iron core
State three factors that affect the strength of an electromagnet.
Number of turns on the coil, the size of the current and the type of core.
State a use of electromagnets.
Loudspeaker, electric bell, circuit breaker.
Explain why the needle of a compass always points in the same direction wherever you point it in a room.
A compass needle always points in a north–south direction. The compass needle lines up in the Earth’s magnetic field.
Define the term solenoid.
A wire wound into a coil.
What is an electromagnet.
A non-permanent magnet turned on and off by controlling the current through it.
What is a magnetic field line?
An imaginary line that shows the direction of the force on a magnetic material.
How can magnetic field lines show the strength of a magnetic field?
The closer the field lines are together, the stronger the magnetic field at that point.
Define the term ‘permanent magnet’.
An object that is magnetic all of the time.
Explain the difference between a permanent magnet and a magnetic material.
A permanent magnet has its own magnetic field, a magnetic material will experience a force if it is placed in a magnetic field.
State two advantages of electromagnets over permanent magnets.
You can turn electromagnets on and off; you can vary the strength of electromagnets and make much stronger electromagnets than permanent magnets.
Explain why iron is used as the core of electromagnet rather than steel.
Iron is easy to magnetise and demagnetise. Steel does not lose its magnetism easily; if you turned the electromagnet off, the steel would still be magnetic.
Complete the sentence: When a _____ flows in a wire it produces a magnetic field around it.
current
Describe how to make an electromagnet.
Wind a coil of wire around a soft iron core and pass a current through it.
State what an atom is.
The smallest part of an element that can exist.
State what a compound is.
Pure substances made up atoms of two or more elements strongly joined together.
What is an element?
Substances that contain only one type of atom.
What is the difference between a compound and a mixture?
A compound is a pure substance made up of atoms of two or more elements strongly joined together; a mixture is a combination of molecules of different atoms and/or compounds jumbled up together and not chemically joined together.
What is a molecule?
A group of two or more atoms strongly joined together.
Name the compound with the formula NO and write down how many of each element are present in the compound.
Nitrogen monoxide; one nitrogen, one oxygen.
What is the chemical formula for carbon dioxide? How many of each element are there in the compound?
CO2 one carbon, 2 oxygen atoms.
What is the name of the compound that contains one sulfur atom and 2 oxygen atoms?
sulfur dioxide.
What is the name of the compound with the formula ZnO?
zinc oxide
What is the name of the compound with the formula NaCl?
sodium chloride
What is the name of the compound with the formula MgS?
magnesium sulfide
What is the name of the compound with the formula CuCO3 ?
copper carbonate
What is the name of the compound with the formula CaSO4 ?
calcium sulfate
What is the name of the compound with the formula KNO3 ?
potassium nitrate
Name the number of each element in the compound with the formula CuCO3 .
1 copper, 1 carbon, 3 oxygen.
Name the number of each element in the compound with the formula CaSO4 .
1 calcium, 1 sulfur, 4 oxygen.
Name the number of each element in the compound with the formula KNO3 .
I potassium, 1 nitrogen, 3 oxygen
Complete the sentence: All the atoms of an element are ______.
the same
Complete the sentence: All the molecules in a compound are ______.
the same
True or false: The properties of a compound are the same as the properties of its elements.
False.
Explain the difference between breathing and gas exchange.
Breathing is the movement of air in and out of the lungs; gas exchange is the movement of oxygen in and carbon dioxide out of the body.
State the scientific name for an air sac.
alveolus
State which gas present in air is not used by the body.
Nitrogen.
True or false: The amount of oxygen in inhaled air is greater than in exhaled air.
True
True or false: The amount of carbon dioxide in inhaled air is greater than in exhaled air.
False
Explain why a person’s breathing rate and volume will increase during strenuous exercise.
During exercise, you require more energy. More oxygen is required so you can respire more. More carbon dioxide is also produced, which needs to be removed.
What happens to the volume and pressure inside your chest when you inhale?
The volume increases, pressure decreases.
What happens to the volume and pressure inside your chest when you exhale?
The volume decreases, pressure increases.
When you inhale, the muscles between the ribs contract. What does this do to the ribcage?
The ribcage moves up and out.
When you inhale, a sheet of muscle underneath the lungs contracts and moves down. What is this muscle called?
The diaphragm.
What happens to the diaphragm when you exhale?
The diaphragm relaxes and moves up.
Give two ways the alveoli are adapted for gas exchange.
Two from: they create a large surface area, have thin walls that are one cell thick and they have a good blood supply.
Name the structure that protects the lungs.
Ribcage
What is the name of the structure that carries air from the mouth and nose to the lungs.
Trachea
Alcohol is a depressant. What does this mean?
Alcohol is a drug that slows down the body’s reactions by slowing down the nervous system.
What is meant by an adiction?
A need to keep taking a drug in order to feel normal.
Name three conditions that smoking can cause.
Heart disease, hear attacks, strokes, breathing problems, cancer, emphysema (a lung disease), respiratory infections.
Name the addictive drug in tobacco smoke.
Nicotine.
Explain why tar found in tobacco smoke is harmful.
Some of the chemicals tar contains cause cancer.
Explain why the carbon monoxide found in tobacco smoke is harmful.
Carbon monoxide stops the blood from carrying as much oxygen as it should. It binds to the red blood cells instead of oxygen.
Write down the equation used to calculate the speed of an object.
Speed = distance / time
How is the speed equation rearranged to find the distance travelled by an object?
Distance = speed x time
How is the speed equation rearranged to find the time taken for an object to travel a given distance?
Time = distance / speed
A car travels 20 metres in 5 seconds. Calculate the speed of the car.
4 m/s
A bike is travelling at 2m/s for 7 seconds. How far does it go?
14 m
A walker travels 30 metres in 1 minute. What is her average speed?
0.5 m/s
Two cars are travelling towards each other at 20m/s. What is their speed relative to each other?
40m/s
A bus is travelling at 15m/s and a car is travelling at 25m/s in the same direction. What is the speed of the car relative to the bus?
10m/s
What does a distance-time graph show?
The distance travelled by an object over time.
What does a straight line on a distance-time graph represent?
A constant speed.
What does a horizontal (flat) line on a distance-time graph represent?
A stationary object.
How would you show an object that is speeding up on a distance-time graph?
A steepening curve.
What does the slope of the line on a distance-time graph represent?
The speed of the object.
The steeper the line on a distance-time graph, the ________ the object is moving.
Faster
How would you show an object that is speeding up on a distance-time graph?
A curve that is levelling off.
True or false: Air resistance and water resistance are non-contact forces.
False.
Air resistance and water resistance are both types of _________.
Drag
Give two factors that can increase the drag acting on an object.
The speed of the object and the surface area of the object.
Explain explain why the drag force on an object increases with the object’s speed.
The object collides with the air particles more frequently and with more force.
Describe how the drag force on an object can be reduced.
Streamlining reduces the drag force. The air flows smoothly around the object, reducing drag.
The vertical columns in the Periodic table are called periods. True or false?
False
Where are metals found in the Periodic Table?
On the left of the stepped line.
Which group are the alkali metals?
Group 1
From top to bottom of the alkali metals, the vigour of the reaction with water increases/decreases. Choose the correct word.
Increases
What is the name given to the elements in Group 7?
Halogens
The elements of which group are referred to as the noble gases?
Group 0
Give two differences between the alkali metals and the noble gases.
Alkali metals are metals and are very reactive; the noble gases are non-metals and very unreactive.
State the name given to the vertical columns in the Periodic Table.
Groups
State the name given to the horizontal rows in the Periodic Table.
Periods
State the meaning of the term unreactive.
Elements that take part in few chemical reactions are unreactive.
Complete the sentence: There are patterns in element properties down ______ and across _______ in the Periodic Table.
Groups, periods
The elements of Group 1 are also known as what?
The alkali metals
The halogens are found in which group of the Periodic table?
Group 7
Group 0 contains which group of elements?
The noble gases
These elements are good conductors of electricity and heat, are shiny when freshly cut and are very reactive. Which group of elements are being described?
Group 1, the alkali metals
Complete the sentence: Metals are on the _______ of the stepped line of the Periodic table.
left
Complete the sentence: Non-metals are on the _______ of the stepped line of the Periodic table.
right
These elements have low melting points and do not conduct electricity. They are also reactive. Which group of elements are being described?
Group 7, the halogens
These elements have very low melting and boiling points, are colourless gases at room temperature and are very unreactive. Which group of elements are being described?
Group 0, the noble gases
Name two elements in Group 7 of the Periodic table.
Fluorine, Chlorine, Bromine, Iodine, Astatine
State what is meant by evolution.
The theory that the animal and plant species living today descended from species that existed in the past.
Describe what a fossil is.
The remains of plans or animals that lived many years ago that have turned to stone.
Describe the process of natural selection.
Variation, survival of the fittest, reproduction, repetition.
Name the process by which organisms evolve.
Natural selection.
Name the organism that Darwin studied on the Galapagos Islands.
Finches
State three pieces of evidence that support Darwin’s theory of evolution.
Fossil record, antibiotic resistant bacteria and extinction.
Explain how Darwin’s finches provide evidence for evolution by natural selection.
The finch species on different islands had different shaped beaks that were adapted to the food they ate.
Explain what it means to say that living things are adapted to their habitats?
This means that they have special features that help them to survive.
Explain how the fossil record provides evidence for evolution by natural selection.
The fossil record provides evidence that organisms have changed over time.
Explain how extinction provides evidence for evolution by natural selection.
Species that do not adapt to environmental changes die out.
What is meant by peer review?
The evaluation of a scientist’s work by another scientist.
Explain what is meant by the phrase ‘survival of the fittest’.
Organisms with the characteristics that are best adapted to the environment survive and reproduce. Less well adapted organisms die.
Can organisms in a species show variation?
Yes.
Complete the sentence: All living organisms have ________ from a common ancestor.
evolved
Name a scientist who developed the theory of evolution by natural selection.
Charles Darwin, Alfred Wallace
What is meant by the term extinct?
When no more individuals of a species remain anywhere in the world.
Before publishing their theories of evolution by natural section, Darwin and Wallace checked each other’s work. What is this process called?
Peer review
Explain the difference between evolution and natural selection.
Evolution is the theory that animals and plants have descended from a common ancestor, natural selection is the process by which evolution occurs.
Complete the sentence: Organisms in a species show _______ - this is caused by differences in their genes.
Variation, survival of the fittest, reproduction, repetition.
Complete the sentence: _______ causes genes from successful organisms are passed to their offspring in the next generation. This means the offspring are likely to possess the same successful characteristics as their parents.
Reproduction
Write down the equation linking mass, weight and gravitational field strength (g).
W=mg
True or false: The mass of an object stays the same wherever it is, but its weight can change.
True
Calculate the weight of a 25kg mass on Earth. (g=10N/kg)
W=mg=25x10=250N
Explain why we experience seasons in the Northern hemisphere.
The Earth’s axis is tilted; in Summer, the Northern hemisphere is tilted towards the Sun, in Winter it is tilted away from the Sun.
Name is the force causing the planets to orbit the Sun and the Moon to orbit the Earth.
Gravity
Name the rocky planets in order of increasing distance from the Sun
Mercury, Venus, Earth, Mars.
Name the gas giant planets in order of increasing distance from the Sun.
Jupiter, Saturn, Uranus, Neptune.
Put these objects in order of size, starting with the largest: Galaxy, star, moon, universe, planet
Universe, galaxy, star, planet, moon
Use the term orbit to explain the difference between a day and a year.
A day is the time taken for a planet to turn once on its axis, a year is the time taken for a planet to make one orbit of its star.
What is a black hole?
An area in space where the force of gravity is so strong that nothing can escape.
Will the Sun become a black hole? Explain your answer.
No, the Sun is not a large enough star.
The distance travelled by light in one year is 9,460,000,000,000 km. What is this also known as?
A light year.
What is the relationship between distance from the Sun and length of year for the planets of the Solar System?
As the distance from the Sun increases, the length of year increases.
A cat has a mass of 4.5kg on the Earth. What would the cat’s mass be on the Moon?
4.5kg
Define the term moon.
A spherical object made of rocky material that orbits a planet
Define the term star.
A large mass that produces heat and light.
Define the term planet.
A spherical object made of rocky or gaseous material that orbits a star.
Define the term galaxy.
A cluster of billions of stars, held together by gravity.
Explain the difference between mass and weight.
Mass is the amount of matter something is made up of, measured in grams (g) or kilograms (kg). Weight is the force acting on an object due to the pull of gravity from the Earth; measured in newtons (N).
What is gravity?
The force of attraction between all objects. The more mass an object has, the larger the force of gravity it exerts.
Write a word equation for the reaction of nitrogen with oxygen to make nitrogen monoxide.
nitrogen + oxygen –> nitrogen monoxide
In the reaction of nitrogen and oxygen to make nitrogen monoxide, name the reactants.
nitrogen and oxygen
In the reaction of nitrogen and oxygen to make nitrogen monoxide, name the product.
nitrogen monoxide
In a chemical reaction, what does the arrow mean?
Reacts to make
True or False: In a chemical reaction, atoms are created.
False. Rearranged, not created.
True or False: In a chemical reaction, the atoms are joined together in different arrangements after the reaction.
True
True or False: In a chemical reaction, the total number of each type of atom is the same after the reaction.
True
State the meaning of the word fuel.
A fuel is a substance that stores energy in a chemical store
Explain what a combustion reaction is.
A chemical reaction in which a substance reacts quickly with oxygen and gives out light and heat. Also called burning.
Methane (CH4) combusts with oxygen to produce carbon dioxide and water. Write down a balanced symbol equation for this reaction.
CH4 + 2O2 –> CO2 + 2H2O
What is meant by a thermal decomposition reaction.
When a single substance breaks down on heating to make more than one product.
When heated, copper carbonate reacts to form copper oxide and carbon dioxide. Write down a word equation for this reaction.
Copper carbonate –> copper oxide + carbon dioxide
When heated, copper carbonate reacts to form copper oxide and carbon dioxide. What is the name of this type of reaction?
Thermal decomposition
State what conservation of mass means
In a chemical reaction, the total mass of reactants is equal to the total mass of products.
Magnesium burns in oxygen to produce magnesium oxide. Write down a word equation, identifying the reactants and products
magnesium + oxygen (reactants) –> magnesium oxide (product)
Magnesium burns in oxygen to produce magnesium oxide. What type of reaction is this?
Combustion
Magnesium burns in oxygen to produce magnesium oxide. Write down a balanced symbol equation for this reaction.
2Mg + O2 –> 2MgO
0.24g of magnesium burns in oxygen to produce 0.40g of magnesium oxide. How much oxygen has reacted with the magnesium?
0.40- 0.24 = 0.16 g
When heated, calcium carbonate produces calcium oxide and carbon dioxide. What type of reaction is this?
Thermal decomposition
When heated, 100 g of calcium carbonate produces 56 gcalcium oxide and how much carbon dioxide?
100 - 56 = 44 g
State what happens in digestion.
Large molecules are broken down into smaller molecules that pass into the blood.
Name the structure that food passes along to reach the stomach.
Oesophagus.
Describe how food moves along the gut.
Muscles in the wall of the gut squeeze food along.
Explain how the villi in the small intestine are adapted to help absorb nutrients into the blood.
The villi have a large surface area and thin walls to absorb more nutrients and contain blood capillaries to carry away the absorbed food molecules.
State three problems caused by being underweight.
Poor immune system, often tired, likely to suffer from a lack of vitamins and minerals.
State three diseases obese people have an increased risk of.
Heart disease, stroke, diabetes, some cancers.
Describe the role of lipids in the body.
Provide a store of energy, keep you warm, protect organs (e.g. kidney and heart) from damage.
Name the nutrient used for growth and repair.
Protein
Explain what is meant by a balanced diet.
Eating food containing the right nutrients in the correct amounts.
Explain the difference between simple and complex carbohydrates.
Simple carbohydrates (e.g. sugars) provide a quick source of energy. Complex carbohydrate (starch) need to be digested so the energy is released more slowly.
What is the food test and positive result for starch?
Starch turns iodine blue-black.
What is the food test and positive result for sugar?
Sugar turns Benedict’s solution orange-red when placed in a water bath.
What is the food test and positive result for protein?
Protein turns Biuret solution purple.
What is the food test and positive result for fat?
Fat makes filter paper transparent.
State the unit that energy in food is measured in.
Joules (J)
What do gut bacteria do?
These microorganisms live in the small intestine and help break food down.
State why the body needs calcium and iron.
Calcium is needed to help maintain healthy teeth and bones; iron is important for making red blood cells.
The enzyme lipase helps to break down which nutrient?
Lipids.
Describe the role of enzymes in digestion.
Enzymes help to break down large nutrient molecules into smaller ones.
Explain why enzymes are called catalysts.
Enzymes speed up digestion without being used up.
Write down the equation used to calculate work done.
Work done = force x distance
What unit is work measured in?
Joules (J)
True or False: Work done and energy transferred are the same thing.
True.
Jane lifts a book onto a high shelf. Which energy store of the book has increased?
Gravitational.
Jane lifts a book from the floor onto a high shelf. The book now has 30J of energy in the gravitational sore. How much work has Jane done?
30J
Stephen moves a block a distance of 0.2m using a force of 4N. How much work has been done?
4 x 0.2 = 0.8J
Sally uses a force of 2N to lift an object 1.5m. How much work is done?
2 x 1.5 = 3J
Give two ways to increase the amount of work done.
Increase the force applied, increase the distance moved.
If you use a 40N force to lift a bag and do 20J of work, how far do you lift it?
20/40= 0.5m
Calculate the work done by a car engine using a force of 500N to move a car 200m.
100,000N
How much work is done by a shopkeeper who uses a force of 50N to lift a box 1.5m.
50 x 1.5 = 75J
How much work is done if a force of 12N moves an object a distance of 5m?
12 x 5 = 60J
Draw a labelled diagram to show how you can use a lever to lift up a heavy box.
Idea that a lever is used with a small input force over a large distance so the large output force moves a small distance.
A pulley system can make it easier to lift a load. The force you use is smaller but the distance your hand moves is _______.
Larger
A car with 1500J of energy in its kinetic store is brought to a stop in 3m. How much force did the brakes apply?
1500/3= 500N
Name two types of simple machine.
Pulleys, levers.
Two pulleys are used to lift a weight of 20N through a distance of 5m. How far does the input force have to move?
2 x 5 = 10m
Three pulleys are used to lift a weight of 45N through a distance of 3m. How much input force is needed?
45/3 = 15N
Explain how using a screwdriver to open a paint tin is useful.
The small input force moves a large distance and so the large output force moves a small distance. This is a force multiplier.
Explain how a human arm is a distance multiplier.
A large inpiut force moves a small distance, so the small output force can move a large distance.
Name the gases that make up the Earth’s atmosphere.
Nitrogen, oxygen, argon, carbon dioxide
Name two greenhouse gases.
Carbon dioxide, methane.
What is meant by the term global warming?
The gradual increase in the air temperature at the surface of the Earth
What percentage of the Eath’s atmosphere is comprised of oxygen?
21%
What percentage of the Eath’s atmosphere is comprised of carbon dioxide?
0.04%
Name two processes that add carbon dioxide to the atmosphere.
Respiration, combustion.
Name two processes that remove carbon dioxide to the atmosphere.
Photosynthesis, dissolving in the oceans
Give two ways that human activities increase the concentration of carbon dioxide in the atmosphere.
Burning fossil fuels, deforestation, farming cattle.
Explain what climate change is
Long term changes to weather patterns
Describe the link between global average air temperature and carbon dioxide concentration.
The patterns in temperature increase and carbon dioxide increase are similar. Human activity is very likely to be the cause.
Which gas makes up about 78% of the Earth’s atmosphere?
nitrogen
What is meant by the term greenhouse gas?
A gas that contributes to the greenhouse effect, such as carbon dioxide.
Explain the greenhouse effect
When energy from the Sun is transferred to the thermal energy store of gases in Earth’s atmosphere, keeping the surface of the Earth warmer than it would otherwise be
Explain why using public transport more often can help reduce greenhouse gas emissions
Using fewer cars, less often. Fewer fossil fuels are burned so less carbon dioxide enters the atmosphere.
Explain why generating electricity from renewable resources can help reduce greenhouse gas emissions
Burning fewer fossil fuels
Explain why buying and wasting less can help reduce greenhouse gas emissions
The processes required to make new things requires burning fossil fuels, mining for resources and/or making space for crops. All of these increase the concentration of carbon dioxide in the atmosphere
Where do all the materials we originally use come from?
Earth’s crust, atmosphere, oceans
What is meant by the term recycling?
Collecting and processing materials that have been used so that these materials can be used again.
Why is it particularly important to recycle some materials?
Resources will not last forever and the faster we extract them, the sooner they will run out.
Give two advantages of recycling.
Resources last longer, uses less energy than extracting new materials, reduces waste and pollution.
Name the chemical reaction that transfers energy from glucose
respiration
State the word equation for aerobic respiration
glucose + oxygen –> carbon dioxide + water
State where in a cell respiration occurs
mitochondria
Name the component of blood that carries oxygen around the body
haemoglobin in the red blood cells
Name thwe component of blood that transports carbon dioxide
plasma
State the word equation for anaerobic respiration
glucose –> lactic acid
Give two reasons why the body normally respires aerbocically
more energy per glucose molecule, lactic acid causes cramp
Give an example of when your body might respire anaerobically.
Strenuous exercise like sprinting
Explain the term oxygen debt.
The extra oxygen needed to break down lactic acid produced from anaerobic respiration.
Explain why your breathing rate increases during exercise
More energy required, so more respiration. More oxygen needed and more carbon dioxide needs to be removed.
Explain why your breathing rate remains high after exercise
Oxygen is required to break down the lactic acid produced from anaerobic respiration.
Give one similarity between aerobic and anaerobic respiration.
Both release energy, both have gluse as a reactant, both chemical reactions.
Give one difference between aerobic and anaerobic respiration.
Aerobic uses oxygen, produces carbon dioxide and water, anaerobic releases less energy, produces lactic acid.
Name the products of anaerobic respiration.
Lactic acid
Name the products of fermentation.
ethanol and carbon dioxide.
What is meant by fermentation
A type of anaerobic respiration performed by plants and microorganisms
State the word equation for fermentation
glucose –> ethanol + carbon dioxide
Give two examples of biotechnology
Making bread, beer and wine
State what is meant by the term biotechnology
The use of biological processes or organisms to create useful products
Name the gas that makes bread rise
Carbon dioxide
